Processing of wood sugar solution



Patented Feb. 5, 1946 2,394,334 rnocnssme F WOOD SUGAR SOLUTION Heinrich Scholler, Munich, Germany; vested in the Alien Property Custodian No Drawing. Application November 28, 1941', Se-

rial No. 420,819. In Germany April 212, 1940 11 Claims. (Cl. 12'l37) This invention relates to the processing of wood sugar solution and particularly to a method for the purification of wood sugar solutions.

Wood sugar solutions of the kind occurring in large quantities in the saccharification of cellulose by hydrolysis with dilute acids, besides simple kinds of sugar also contain considerable proportions of undesirable admixtures which are detrimental for some purposes, for instance, where baking yeast is to be produced from wood sugar, or where wood sugar is to be used as an animal foodstuff or as an initial product for the production of crystallised dextrose.

It is an important object of the present invention to provide a method which in a simple manner permits separation of said admixtures from the wort to a degree of purity sufilcient for t; said purposes, which was not hitherto poss e. i

I have now found that after thickening of the wood sugar solution, for instance, to a specific gravity of 1.35, and after letting thesubstance stand for a period of several hours, at temperatures above 60 0., and extensive resinification of the undesirable admixtures takes place. Vacuum may be used for thickening the solution, if desired.

The separation products may be removed from the sugar solution by centrifuging, filtering, clarifying or by decantation. By way of alternative,

said treatments may be used in combination. Since the resinous separations partly are agglomerated, they may also be removed by sieving, i. e., by clearing.

The resinification may be carried .out at tem-= peratures below or above 100 C., but a tempera- I ture range of 90 to 100C. will be preferable since below 80 C. the process proceeds very much more slowly, while the application of considerably higher temperatures would require the use of pressure vessels without offering substantial advantages. Preferably the process is carried out in the vicinity of the neutral point or in a slightly acid condition.

It is of special importance for the process of resinifications that an optimum specific gravity is maintained. I have found that the resinification proceeds very well at a specific gravity of 1.3 to 1.4. It is desirable to ascertain the optimum specific gravity for each raw material by preliminary tests.

The heat treatment is carried through for several hours, preferably under stirring, the actual length of time for this treatment depending of purity. After the wort has been heat-treated for several hours, the same is, suitably cooled down to a temperature below and let stand for several hours, whereby the separation and removal of. the resinous products is promoted.

My novel method primarily relates to the treatment of wood sugar worts produced after the percolation method from leaf wood or coniferous trees, but sugar worts made from other cellulose-containing substances may also be purified after my novel process. My process is adapted especially also for the refining of the various percolation fractions obtained according to the process described in my U. S. Patentv No. 2,188,193, in which the first fractions are separated and used for the production of pentoses,.while the later fractions of the percolation process serve for the manufacture of crystallised dextrose. My novel method may housed in any of these and similar cases. One or more frac-. tions-of the Wood sugar solution, if desired or required the later fractions, containing about the second half of the yield of reducing sugar, may be treated separately. For instance, by evaporation and crystallisation of the later fractions, without application of my purifying method, a crystallised product has been obtained containing about parts by weight of dextrose in arts dry substance, while in a comparative test, starting from solutions subjected to a preliminary treatment according to the present invention, a product containing 98 to. 99 percent glucose per 100 parts by weight has been obtained already in the first crystallisation, after centrifuging in known manner. The crystallisation may be carried out according to the methods known in the art for glucose.

In order to facilitate the separation of the resinous products from the solution by means of centrifuging, filtering, clearing or decanting, a certain amount of water is advantageously added thereo. The separation may be facilitated considerably bya reduction of the specific gravity by dilution to a figure of 1.28 to 1.30.

The removal of the deposit or precipitate may take place immediately upon addition of the water. Upon removal of the precipitates the clear solution is suitably concentrated again so as'to meet the purpose for which it is intended.

The separation products are soluble entirely or partly in alkalis, ketones, alcohols, and in furfurol, and may be used for the production of varnishes or lacquers and mordants, either alone or admixed with shellac. The wood sugar soluon the initial product and the desired degree 55 tions'thus purified and thickened are adapted and preferably 1.39.

not only for the production of crystallised dextrose but also for the production of baking yeast and for use as animal food material, or as a constituent for mixed animal foodstufi. The mother liquors occurring in the crystallising processafter repeating the above described purifying process, if desired-may also be used for the manufacture of baking yeast or as an animal food material.

Example The later fractions of a percolation process containing about one-half of the total amount of sugar after being neutralised by means of ground limestone are evaporated under vacuum to a specific fravity of 1.34, and then maintained, for a period of about eight hours, at a temperature of 90 to 100 C., under stirring, this resulting in the separation of resinous masses. After eight hours treatment the solution is cooled down and let stand for several hours, whereupon the specific gravity is adjusted to specific gravity 1.28 by addition of water. are removed from the solution, by centrifuging in solid jacket centrifugal machines.

The resinous masses are subsequently washed by means of water and dried. The yield of resinou products amounts to about 5 to percent by weight of the total dry substance of the sugar solution.

The purified sugar solution then is boiled down under vacuum to a specific gravity of 1.35 to 1.40,

The solution thus processed may be crystallised according to the methods known in the art forstarch sugar.

The method of the present invention has been described in detail with reference to specific embodiments. It is to be understood, however, that the invention is not limited by such specific reierence-but is broader in scope and capable of other embodiments than those specifically described. Y

I claim:

1. In a method of purifying wood sugar solutions, obtained from cellulose material by hydrolysis with dilute acids, the steps which comprise concentrating the solutions to a specific gravity from 1.2 to 1.4, then maintaining the solutions at a temperature of 60 C. to 100 C., for

a period of several hours, and finally separating the resinous constituents from the sugar solution.

2. In a method of purifying wood sugar solutions, obtained from cellulose material by hydrolysis with dilute acids, the steps which comprise concentrating the solutions to a specific gravity from 1.2 to 1.4, then maintaining the solutions at a temperature of 60 C. to 100 C., under stirring, for aperiod of several hours, and finally separating the resinou constituents from the sugar solution.

3. In a method of purifying wood sugar solutions, obtained from cellulose material by hydrolysis with dilute acids, the steps which comprise concentrating the solutions to a specific gravity from 1.2 to 1.4, then maintaining the solution at a temperature of 90 to 100 C., for a period of several hours, and finally separating the resinous constituents from the sugar solution.

Then the resinous masses- 4. In a method of purifying wood sugar solutions, obtained from cellulose material by bydrolysis with dilute acids, the steps which comfrom the sugar solution.

5. In a method of purifying wood sugar solutions, obtained from cellulose material by hydrolysis with dilute acids, the steps which comprise concentrating the solutions to a specific gravity from 1.2 to 1.4, then maintaining the solutions at a temperature of 80 to 100 C. for a period of eight hours, the solutions being adjusted by the addition of water to have a slightly acid reaction during heat treatment, and finally separating the resinous constituents from the sugar solution.

6. In a method of purifying wood sugar solutions, obtained from cellulose material by hydrolysis with dilute acids, the steps which comprise concentrating the solutions to a specific gravity from 1.2 to 1.4, then maintaining the solutions at a temperature of 60 C. to 100 C., for a period of several hours, cooling the solution to a temperature below C., letting stand the solution for a period of several hours, and finally separating the resinous constituents from the sugar solution.

7. A method according to claim 1, in which the solution obtained after separation of the resinous masses by further concentrating is adjusted to a specific gravity of 1.35 to 1.40, the glucose then being crystallised.

8. A method according to claim 1, in which the wood sugar solution upon separation of the resinous constituents is diluted with water, whereby the removal of said constituents is facilitated.

9. A method according to claim 1, in which the wood sugar solution upon separation of the resinous constituents is diluted with water, whereby the removal of said constituents is facilitated, the solution being concentrated again upon removal of said constituents.

10. In amethod of purifying wood sugar solutions, obtained from cellulose material, by hydrolysis with dilute acids, the steps which comprise cencentrating the solutions to a specific gravity of from 1.3 to 1.4, then maintaining the solutions at a temperature of C. to C., for a period of several hours, diluting the solutions to a specific gravity of from 1.28 to 1.30, and separating the resinous constituents from the sugar solution.

11. In a method of purifying wood sugar solutions, obtained from cellulose material, by bydrolysis with dilute acids, the steps which comprise concentrating the solutions to a specific gravity of from 1.3 to 1.4, then maintaining the solutions at a temperature of 60 C. to 100 C., for a period of several hours, cooling the solutions t a temperature below 50 C., and separating the resinous constituents from the sugar solution.

HEINRICH SCHOLLER. 

